This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Subproject #1: Th Cells in Theiler's Virus Persistence and Pathology Ikuo Tsunoda, MD, PhD In this project, we will clarify the role of subsets of helper T (Th) cells [Th1, Th2, Th17, and regulatory T (Treg) in viral persistence and pathology using a viral model for multiple sclerosis (MS), Theiler's murine encephalomyelitis virus (TMEV) infection. Th-related molecules, including cytokines, have been investigated in MS research mainly using blocking antibodies and gene knockout mice. Although immune-mediated diseases can be mediated by cytokine deficiency or overexpression, T-bet (Th1 specific) or GATA3 (Th2 specific) transgenic (Tg) mice have not been used in animal models for MS. In this proposal, we will use the T-bet and GATA3 Tg mouse systems to determine the influence of cytokine overexpression in a viral model for MS. Using these novel Tg mice, we will also examine an interaction between Th1, Th2, Th17, and Treg cells by administration of LPS which can increase Th17 cells or by adoptive transfer of Treg cells in the TMEV model. Treg transfer experiments will be conducted with collaboration from Dr. Matthew B. Grisham, who has developed a novel ex vivo method to generate large numbers of green fluorescent protein (GFP)+Foxp3+ Treg cells that can be used in vitro and in vivo to suppress the activation, polarization and expansion of Th1/Th17 cells. In Aim 1, we will use Th1 or Th2 cytokine overexpressing Tg mice infected with TMEV. In Aim 2, we will induce Th17 cells or Treg cells and clarify their role in TMEV infection. In Aim 3, we will compare the role of Th cells between resistant C57/BL6 mice versus susceptible SJL/J mice, using microarray and immunological and pathological profiles. Achievement of aims in this project will allow us to add insight about possible associations between Th cells and persistent viral infection as well as pathology of MS. This will drive the development of tailor-made interventions of viral mediated immunopathology and/or MS, whose treatment can be dependent on immunological backgrounds.